High blood cholesterol levels are associated with life threatening cardiovascular diseases. Cholestyramine and colestipol hydrochloride are drugs used in treating hypercholesterolemia. These drugs are known as basic anion exchange resins. They help to lower blood cholesterol levels apparently by binding to bile acids in the intestine. It is believed that this in turn causes an increase in hepatic metabolism of cholesterol to replenish the bile acids lost to complexation with the anion exchange resins.
Cholestyramine is usually dosed at four grams (anhydrous weight), one to six times daily. At the present time cholestyramine is commercially available as Questran.RTM. and Questran.RTM. Light (manufactured by the Bristol-Myers Squibb Company) in a four gram unit dose powder packet or in bulk powder. Physicians Desk Reference, 49th Edition, pages 735-739 (1995).! Cholestyramine is commercially available as Duolite AP-143 resin (Rohm & Haas Co.).
Colestipol hydrochloride is usually administered at five to thirty grams daily given once or in divided doses. Colestipol hydrochloride is commercially available under the tradename Colestid.RTM. (colestipol hydrochloride granules, manufactured by The Upjohn Company). It is sold in a five gram unit dose powder packet or in bulk powder. Physicians Desk Reference 49th Edition, pages 2531-2534 (1995)!.
While the benefits of anion exchange resins are well known and appreciated, the aesthetics (e.g., mouthfeel, taste, and throat sticking) are considered by many users to be very unacceptable. The unpleasant mouthfeel of cholestyramine is frequently described as a sandy, gritty texture which tends to stick to the back of the mouth and throat upon ingestion and which leaves an unpleasant fishy taste in the mouth. Colestipol hydrochloride is described as having an astringent taste and a sandy, gritty texture which sticks to the mouth and teeth after ingestion. Obviously, poor aesthetics raise concern about how closely patients will comply with any treatment regimen using these agents.
Research has been done in an effort to improve the palatability of anion exchange resins. Patents which disclose such efforts include: French Medical Patent 6,888 M published Jun. 4, 1964 by Mead Johnson & Company which 35 describes dry mixing acacia gum with cholestyramine resin to aid in making the astringency of cholestyramine disappear; and U.S. Pat. No. 3,974,272 to Polli et al., issued Aug. 10, 1976 which describes a palatable oral coacervate composition containing cholestyramine and a modified gum selected from hydrophilic colloid of cellulosic material and charged anionic gum in an aqueous medium.
Despite the research aimed at improving the compositions containing anion exchange resins, a great need still exists for compositions that provide therapeutic benefit while maintaining an agreeable texture and taste, thereby encouraging patient compliance with the treatment regimen. It has been discovered in the present invention that combining an anion exchange resin, such as cholestyramine or colestipol hydrochloride, with xanthan gum aids in masking the unpleasant taste and mouthfeel associated with these resins. It has also been discovered that such compositions can be formulated as aesthetically pleasing drink mix compositions. This improvement in aesthetics has the advantage of further enhancing compliance of an individual receiving an anion exchange resin therapeutic regimen.
These and other objects of the present invention will become readily apparent from the detailed description which follows. All percentages and ratios used herein are by weight unless otherwise specified. Screen mesh sizes used herein are based on U.S. standards. The abbreviation "g", as used herein refers to "grams".